Lead alloy



Patented June 20', 1939 UNITED STATES PATENT OFFICE LEAD ALLOY No Drawing. Application March 24, 1936,

Serial No. 70,607

1 Claim.

This invention relates to lead alloys and particularly concerns the improvement of certain lead alloys with respect to their oxidizing characteristics.

In the manufacture of cable sheathing, pipe. sheeting and the like, it has long been the practise to utilize lead containing a small amount of another metal or other metals which impart to the alloy certain desired characteristics, e. g. increased tensile strength, improved resistance to corrosion, greater hardness, etc. ments used either singly or with others for this purpose, which will hereinafter-be referred to as improvement metals, antimony, arsenic, bismuth, cadmium, calcium, magnesium, tin and zinc are the more important.

While such lead alloys have proven themselves superior to. lead with-respect to the properties for which they have been employed, nevertheless a an undesired characteristic accompanies the addition of these improvement metals to lead namely, their -general tendency toward excessive oxidation.

That the susceptibility of alloys of lead and oxidation is a serious disadvantage is very apparent in the extrusion of cable sheathing where the oxidation products become incorporated in the sheath causing weakness and areas favoring the inception of corrosion.

It has now been found that by incorporating phosphorus in amounts not exceeding approximately 0.01 in a lead alloy containing not more than approximately 0.5% of improvement metal or metals, the tendency of the alloy toward excessive oxidation is reduced to a very great extent and this highly desirable result is obtained without materially afiecting the tensile strength of the composition.

In determining the oxidation of the various compositions investigated, the following procedure was followed in all cases: a 500 gram sample of the composition was melted in a casserole and the surface stirred for ten minutes at a temperature of 355 C. by means of a rotating paddle operated at 100 R. P. M. The dross was then skimmed and weighed after which the oxide was dissolved in molten zinc chloride. Upon solidification the mass was lixiviated with water and the remaining lead button weighed. The difference between the weight of the dross skimmed and the weight of the lead button was the weight of the oxide formed in the particular test.

The following tabulated results with alloy! of Among the ele-' the aforesaid improvement metals'to excessive antimony and cadmium, two of the most common improvement metals in cable sheathing, will serve to illustrate the invention:

Composition Grams oxide Refined Pb 0. 350 Refined Pb+0.20% Cd 4. 171 Refined Pb+0.-20% Cd+0.003% P... 2. 162 Refined Pb+0.20% Cd+0.007% P 0. 460 Refined Pb+0.03% Sb 4. 799 Refined Pb+0.03% Sb+0.003% P 1.544 Refined Pb+0.03% Sb+0.007% P 1.022

' Tensile Composition strength (Psi) Refined P 1905 Refined Pb+0.20% As+0.007% P $25 Refined Pb+0.05% Sb+0.007% P 2920 Refined Pb+0.20% Cd 3120 Refined Pb+0.20% Cd+0.003% P 3120 It will thus be appreciated that the present invention provides lead alloys which are admirably adapted for cable sheathing and the like. As before stated the improvement metal content should not be more than approximately 0.5% and investigations indicate that an improvement metal content of from 0.05% to 0.3% is, generally speaking, to be preferred. The phosphorus content should range between'0.001% and 0.01%. Material departure from these phosphorus and improvement metal or metals ranges should not be indulged in as the amount of phosphorus necessary to counteract the increased oxidation accompanying material increases of improvement metals would adversely afiect other desired properties of the particular alloy.

What is claimed is:

An alloy consisting of cadmium in an efiective amount but not exceeding 05%, phosphorus in an efiective amount but not exceeding 0.01% and. the balance lead.

- JESSE 0. IBEI'I'ER'IDN. YURI! 8. manner. I 

